Mont Blanc Tunnel, Chamonix

The Mont Blanc Tunnel is a crucial highway tunnel that connects Chamonix, Haute-Savoie, France, with Courmayeur, Aosta Valley, Italy, running beneath the Mont Blanc mountain in the Alps. This passage serves as part of the European route E25, integrating the French Route Nationale 205 and the Italian Traforo T1. It is a key trans-Alpine transport link, particularly vital for Italy, facilitating the movement of approximately one-third of its freight to northern Europe. The tunnel significantly reduces the travel distance to Turin by 50 kilometers (30 miles) and to Milan by 100 kilometers (60 miles). Positioned about 15 kilometers (10 miles) southwest of the Swiss tripoint near Mont Dolent, it is a strategic artery for cross-border traffic.

The decision to construct the Mont Blanc Tunnel was formalized in 1949 through an agreement between France and Italy. To oversee the project, two operating companies were established: Highways and Mont-Blanc Tunnel in France on April 30, 1958, and Italian Joint-Stock Company for the Mont Blanc Tunnel on September 1, 1957. Drilling commenced in 1959 and was completed by 1962, with the tunnel officially opening to traffic on July 19, 1965.

Spanning 11.611 kilometers (7.215 miles) in length, the tunnel is 8.6 meters (28 feet) wide and 4.35 meters (14.3 feet) high. Its profile features a slightly inverted “V” shape, aiding in natural ventilation. The single-gallery tunnel accommodates a two-lane, bi-directional road. At the time of its construction, it was the longest highway tunnel globally, at three times the length of existing tunnels.

The tunnel runs nearly directly beneath the summit of the Aiguille du Midi, at a depth of 2,480 meters (8,140 feet) below the surface. This makes it the second deepest operational tunnel in the world, surpassed only by the Gotthard Base Tunnel.